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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Be Book - System Overview - The Input Server</title><link rel="stylesheet" href="be_book.css" type="text/css" media="all" /><link rel="shortcut icon" type="image/vnd.microsoft.icon" href="./images/favicon.ico" /><!--[if IE]>
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<![endif]--><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="keywords" content="Access, BeOS, BeBook, API" /><link rel="start" href="index.html" title="The Be Book" /><link rel="up" href="TheInputServer_Overview.html" title="The Input Server" /><link rel="prev" href="BInputServerFilter_Overview.html" title="BInputServerFilter" /><link rel="next" href="TheInterfaceKit_Overview.html" title="The Interface Kit" /></head><body><div id="header"><div id="headerT"><div id="headerTL"><a accesskey="p" href="BInputServerFilter_Overview.html" title="BInputServerFilter"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a accesskey="u" href="TheInputServer_Overview.html" title="The Input Server"><img src="./images/navigation/up.png" alt="Up" /></a> <a accesskey="n" href="TheInterfaceKit_Overview.html" title="The Interface Kit"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="headerTR"><div id="navigpeople"><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div><div class="navigboxed" id="navigindex"><a accesskey="i" href="ClassIndex.html" title="Index">I</a></div><div class="navigboxed" id="naviglang" title="English">en</div></div><div id="headerTC">The Be Book - System Overview - The Input Server</div></div><div id="headerB">Prev: <a href="BInputServerFilter_Overview.html">BInputServerFilter</a>  Up: <a href="TheInputServer_Overview.html">The Input Server</a>  Next: <a href="TheInterfaceKit_Overview.html">The Interface Kit</a></div><hr /></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h2 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BInputServerMethod_Overview"></a>BInputServerMethod</h2></div></div></div><p><a class="link" href="BInputServerMethod.html" title="BInputServerMethod"><code class="classname">BInputServerMethod</code></a>
is a base class for input methods; these are instances
of <a class="link" href="BInputServerMethod.html" title="BInputServerMethod"><code class="classname">BInputServerMethod</code></a>
that act as an interface between the user and
languages using character sets that can't be easily represented on
standard keyboards, such as the Japanese input method that comes with
BeOS.</p><p>Input methods generally handle <code class="constant">B_KEY_DOWN</code>
messages in their
<a class="link" href="BInputServerFilter.html#BInputServerFilter_Filter" title="Filter()"><code class="methodname">Filter()</code></a>
function (see
<a class="link" href="BInputServerFilter.html" title="BInputServerFilter"><code class="classname">BInputServerFilter</code></a>),
keeping some sort of state around to translate these standard
keyboard messages into new <code class="constant">B_KEY_DOWN</code> messages
representing another character set. An input method can handle any input
event, they're not limited to keyboard events.</p><div class="admonition warning"><div class="title">Warning</div><div class="graphic"><img class="icon" alt="Warning" width="32" src="./images/admonitions/Stop_32.png" /><div class="text"><p>Writing an input method is an involved process, even though the
<code class="classname">BInputServerMethod</code>
protocol is relatively simple. If you're working on an input
method, please feel free to contact Be Developer Technical Support
(devsupport@be.com) for additional information.</p></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BInputServerMethod_InputMethodEvents"></a>Input Method Events</h3></div></div></div><p>Input methods insert <code class="constant">B_INPUT_METHOD_EVENT</code> messages (using their
<a class="link" href="BInputServerMethod.html#BInputServerMethod_EnqueueMessage" title="EnqueueMessage()"><code class="methodname">EnqueueMessage()</code></a>
function) into the Input Server's event stream. These
messages let <a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>
subclasses work together with your input method to
create a seamless experience for the user.</p><p>Each <code class="constant">B_INPUT_METHOD_EVENT</code> message contains a
<code class="varname">be:opcode</code> field (an <span class="type">int32</span>
value) indicating the kind of event:</p><table class="variablelist constants"><thead><tr><th>Constant</th><th>Description</th></tr></thead><tbody><tr><td><p><span class="term"><code class="constant">B_INPUT_METHOD_STARTED</code></span></p></td><td><p>Indicates that a new input transaction has begun.
Add a <a class="link" href="BMessenger.html" title="BMessenger"><code class="classname">BMessenger</code></a>
in the <code class="varname">be:reply_to</code> field; the receiver of the message
will use this messenger to communicate with you during the transaction.</p></td></tr><tr><td><p><span class="term"><code class="constant">B_INPUT_METHOD_STOPPED</code></span></p></td><td><p>Indicates that the transaction is over.</p></td></tr></tbody></table><p>In between the <code class="constant">B_INPUT_METHOD_STARTED</code> and <code class="constant">B_INPUT_METHOD_STOPPED</code>
messages, you'll send <code class="constant">B_INPUT_METHOD_CHANGED</code> and
<code class="constant">B_INPUT_METHOD_LOCATION_REQUEST</code> messages as the transaction proceeds.</p><p><code class="constant">B_INPUT_METHOD_CHANGED</code> does most of the work in
an input transaction; add the following important fields:</p><div class="informaltable"><table border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th>Entry</th><th>Type</th><th>Description</th></tr></thead><tbody><tr><td><code class="varname">be:string</code></td><td><code class="constant">B_STRING_TYPE</code></td><td>The text the user is currently entering; the
receiver will display it at the current insertion point.
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
also highlights the text in blue to show that it's part of a transitory
transaction.</td></tr><tr><td><code class="varname">be:selection</code></td><td><code class="constant">B_INT32_TYPE</code></td><td>A pair of B_INT32_TYPE offsets into the
<code class="varname">be:string</code> if part of <code class="varname">be:string</code> is
current selected. <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
highlights this selection in red instead of drawing it in blue.</td></tr><tr><td><code class="varname">be:clause_start</code></td><td><code class="constant">B_INT32_TYPE</code></td><td>Zero or more offsets into the <code class="varname">be:string</code> for
handling languages (such as Japanese) that separate a sentence or phrase
into numerous clauses. An equal number of <code class="varname">be:clause_start</code> and
<code class="varname">be:clause_end</code> pairs delimit these clauses;
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a> separates the
blue/red highlighting wherever there is a clause boundary.</td></tr><tr><td><code class="varname">be:clause_end</code></td><td><code class="constant">B_INT32_TYPE</code></td><td>Zero or more offsets into <code class="varname">be:string</code>; there
must be as many <code class="varname">be:clause_end</code> entries
as there are <code class="varname">be:clause_start</code>.</td></tr><tr><td><code class="varname">be:confirmed</code></td><td><code class="constant">B_BOOL_TYPE</code></td><td>True when the user has entered and "confirmed"
the current string and wishes to end the transaction.
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
unhighlights the blue/red text and waits for a <code class="constant">B_INPUT_METHOD_STOPPED</code> (to
close the transaction) or another <code class="constant">B_INPUT_METHOD_CHANGED</code> (to start a new
transaction immediately).</td></tr></tbody></table></div><p><code class="constant">B_INPUT_METHOD_LOCATION_REQUEST</code> is the input method's way of asking for
the on-screen location of each character in <code class="varname">be:string</code>. This information
can be used by the input method to pop up additional windows giving the
user an opportunity to select characters from a list or anything else
that makes sense. When you send a <code class="constant">B_INPUT_METHOD_LOCATION_REQUEST</code>, the
receiver will reply to the <code class="varname">be:reply_to</code> messenger (that you sent in your
<code class="constant">B_INPUT_METHOD_STARTED</code> message) with a <code class="constant">B_INPUT_METHOD_EVENT</code> message,
filling in the following fields:</p><div class="informaltable"><table border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th>Entry</th><th>Type</th><th>Description</th></tr></thead><tbody><tr><td><code class="varname">be:opcode</code></td><td><code class="constant">B_INT32_TYPE</code></td><td>Set to <code class="constant">B_INPUT_METHOD_LOCATION_REQUEST</code>.</td></tr><tr><td><code class="varname">be:location_reply</code></td><td><code class="constant">B_POINT_TYPE</code></td><td>The co-ordinates of each character (there
should be one <code class="varname">be:location_reply</code> for every
character in <code class="varname">be:string</code>)
relative to the display (not your view or your window).</td></tr><tr><td><code class="varname">be:height_reply</code></td><td><code class="constant">B_FLOAT_TYPE</code></td><td>The height of each character in <code class="varname">be:string</code>.</td></tr></tbody></table></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BInputServerMethod_Creating"></a>Creating</h3></div></div></div><p>To create a new input method, you must:</p><ul class="itemizedlist"><li><p>Create a subclass of
<a class="link" href="BInputServerMethod.html" title="BInputServerMethod"><code class="classname">BInputServerMethod</code></a></p></li><li><p>Implement the <code class="function">instantiate_input_method()</code> C function to create an
instance of your
<a class="link" href="BInputServerMethod.html" title="BInputServerMethod"><code class="classname">BInputServerMethod</code></a>
subclass</p></li><li><p>Compile the class and function as an add-on</p></li><li><p>Install the add-on in one of the input method directories</p></li></ul><p>At boot time (or whenever the Input Server is restarted; see "Dynamic
Loading"), the Input Server loads the add-ons it finds in the input
method directories. For each add-on it finds, the Server invokes
<code class="function">instantiate_input_method()</code> to get a pointer to the add-on's
<code class="classname">BInputServerMethod</code> object. After constructing the object, the Server
calls <code class="methodname">InitCheck()</code> to give the add-on a chance to bail out if the
constructor failed.</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BInputServerMethod_InstallingAnInputMethod"></a>Installing an Input Method</h3></div></div></div><p>The input server looks for input methods in the "input_server/methods"
subdirectories of <code class="constant">B_BEOS_ADDONS_DIRECTORY</code>,
<code class="constant">B_COMMON_ADDONS_DIRECTORY</code>, and
<code class="constant">B_USER_ADDONS_DIRECTORY</code>.</p><ul class="itemizedlist"><li><p>You can install your input devices in the latter two
directories—i.e. those under <code class="constant">B_COMMON_ADDONS_DIRECTORY</code>, and
<code class="constant">B_USER_ADDONS_DIRECTORY</code>.</p></li><li><p>The <code class="constant">B_BEOS_ADDONS_DIRECTORY</code> is reserved for add-ons that are supplied
by the BeOS.</p></li></ul></div></div><div id="footer"><hr /><div id="footerT">Prev: <a href="BInputServerFilter_Overview.html">BInputServerFilter</a>  Up: <a href="TheInputServer_Overview.html">The Input Server</a>  Next: <a href="TheInterfaceKit_Overview.html">The Interface Kit</a> </div><div id="footerB"><div id="footerBL"><a href="BInputServerFilter_Overview.html" title="BInputServerFilter"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a href="TheInputServer_Overview.html" title="The Input Server"><img src="./images/navigation/up.png" alt="Up" /></a> <a href="TheInterfaceKit_Overview.html" title="The Interface Kit"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="footerBR"><div><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div></div><div id="footerBC"><a href="http://www.access-company.com/home.html" title="ACCESS Co."><img alt="Access Company" src="./images/access_logo.png" /></a></div></div></div><div id="licenseFooter"><div id="licenseFooterBL"><a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/" title="Creative Commons License"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by-nc-nd/3.0/88x31.png" /></a></div><div id="licenseFooterBR"><a href="./LegalNotice.html">Legal Notice</a></div><div id="licenseFooterBC"><span id="licenseText">This work is licensed under a
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